Call-distributing system



S. B. WILLIAMS, JR. CA LL DISTRIBUTING SYSTEM.

7 APPLICATION FILED APR. 14, I919- I 1 36 74 Patented Aug; 9, 1921,

5 SHEETSSHEET l- S. B. WILLIAMS, JR.

CALL DISTRIBUTING SYSTEM. APPLICATION FILED APR. 14. 1919.

Patented Aug. 9, 1921.

5 SHEETS-SHEET 2.

s. B. WILLIAMS, in.v CALL DISTRIBUTING SYSTEM. APPLICATION FILED APR; 14, I919- Patented Aug. 9, 11.9211.

swans-sun 3.

s. B. WILLIAMS, Jn= CALL DISTRIBUTING SYSTEM.

APPLICATION FILED APR- 14, I919- 1,38@,749u Patented Aug. 9, 19211,

5 SHEETS-SHEET 4' II I- Awe/7m".- Ja/m/e/ 5. W/W/am, Jr.

S. B. WILLIAMS, In.

' CALL DISTRIBUTING SYSTEM.

APPLICATION FILED APR. 14 I919- 19 @6p?%9o I 9, 19210 5 SHEETS-SHEEP? I cairn srarss SAMUEL LB. WILLIAMS, JR., 0F BEOOKLYN, NE'W YORK, ASSIGNOE TO WESTERN ELEC- TRIO COMPANY, INCORFORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Specification of Letters Patent.

CALL-DISTRIBUTING SYSTEMI.

Patented Aug. 9, 1921.

Refiling' of abandoned application Serial No. 107,090, filed July 1, 1916. This application filed April 14,

To all whom it may concern:

Be it known that I, SAMUEL B. WILLIAMS, Jr., a citizen of the United States, residing at Brooklyn, in the county of Kings and vFltate of New York, have invented certain new and useful Improvements in Call-Distributing Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to systems oi the type employing automatic HRVliICllQS for distributing calls to the connecting circuits of operators positions.

The present invention is a division of that disclosed and originally claimed in applicants case, Serial No. 107,090, filed July 1, 1916.

The present invention is shown in a telephone system in which calling subscribers lines are distributed to an operators connecting circuit through the agency of one or more automatic switches; in which traffic is distributed in such a way as to keep the operators positions uniformly busy; in which the calls are extended to operators positions that are at that time unengaged and diverted from those positions that are busy; and in which each calling line is extended to only one of the operators positions that may at the time be ready to receive a call.

The object of the present invention is to provide a registering device associated with an operators position which is effective on the extension of a call to count or charge the service given.

Other objects to which this invention is directed and which are attained in the system herein disclosed, will appear in connection with the detailed description that follows.

The preferred embodiment of the system ot the invention is illustrated in the accompanying diagrammatic, drawings, in which Figure 1 shows two groups of lines with two line finder switches for making connection therewith, together with the associated circuits and apparatus through the medium of which the lines control the switches; Fig. 2 shows one finder circuit complete, and, enough of two other finder circuits to illustrate the relationship between them; Fig. 3 shows two cord selector switches of one iraniewith their associated selection con- Serial No. 290,065.

trolling apparatus and circuits together wlth similar apparatus and circuits for the cord selector switches (not shown) of another i'rame; Fig. 4 shows the position apparatus and circuits of one operators position, with enough of the position apparatus of another position to illustrate the interrelation oi the two; and Fig. 5 shows one connecting cord circuit complete, together with certain inter-related parts of other cord circuits located on the same operators position, also one of the called lines with which the cord circuit may be connected. The figures taken together, and arranged side by side in the order indicated by the lines that extend to the margins of the sheets, illustrate as much of a complete organization as is necessary to gain an understanding of the construction and mode of operation of the system.

Two telephone lines are indicatedin each of the two groups shown in Fig. 1, it being understood that each group may comprise a large number of such lines. Thepractice is to give the finder switch brushes access to the terminals of five hundred lines, these.

lines being arranged in ten groups of fifty lines each. Each of the lines has associated with it at the central o ifice a line relay12, a cut-off relay 11 and, it it is a message-rate line, a connection register 164. Each line is also provided with one or, more spring jacks by means of which connection may be made with the line when it is a called line. The lines represented as calling lines in Fig. 1 and the line shown as a called line in Fig. 5 may be lines of the same sort, similarly equipped and located at the same exchange; or the lines may be located at different oflices. In the present instance, the

called line shown in Fig. 5 is indicated as being provided with connections by means of which it may have control over finder switch mechanism in the manner illustrated in connection with thelin es of Fig. 1. Each group or lines, LG and LG, hasassociated with it certain group apparatus consisting of two relays 19 and 24, and a timing seof finder circuits F, F, and F which termicuits extending. to inultipled groups of terna'te upon the brushes of pairs of finder switches of which two sets, LF and CS" and LIV and C5, are shown. Each of the groups of connecting circuits is associated with. a particular operators position, of

which the apparatus of one is shown at 0 and the apparatus of theothei' is partially shown at 0. 'In the particular system illustrated, itisthe practice to provide each operators position with twenty connecting cir minals upon the cord'selector switches, and

togive the'brushes of each cord selector switch access to the terminals of twenty-five such groups'of connecting circu ts. But one of the connecting circuits is shown complete,

.the other connecting circuits in the associated lOll) and in the other 'rou as bein b b b assumed to be similarly organized and connected. The multipleconnections of thecoiinecting circuit with the terminals of the cord selector switches are shown in thecase of the connecting circuit that is completely illustrated; and in like manner the multiple connections of .the telephone line with the terminals of the line finder switches are shown iii-the case of the line that extends from station A. The multiple connections that exist between corresponding sets of switch terminals for the other connecting circuits and telephone lines are omitted to avoid confusing the drawing.

A number; of groups of cord selector switches likethe group illustrated in Fig. 3 may have access to the same groups of connecting circuits and their corresponding op- 'erators positions. This is indicated in Fig.v

3.- 'Eac'hof the groups of'cord selector 1 switches has associated with it certain selection controlling apparatus, that associated with the cord selector switches shown in Fig. 3' appearing under the caption Frame "each frame or groupof cord selector switches comprises a set'of relays 77 93 and 94.- for "2, and that associated with the "cord se "lector switches ofthe other group that is not shown appearing under'the caption Frame 1. The selection controlling-apparatus for each'group, CG, CG", tO'WlilCll the cord sementioned groups.

lector has access, and a group of relays 54,

55, 61 and 63,- comm-on to all of the first As the line finder switches LF and LF, and the cord selectorswitchesCS and CS in themselves arenot novel, they are shown merely diagrammatically. These switches may be sub'stantial1y like the switch illus- 'trated and described'in the patent to James -L. McQuarrie, No. 1,177,044,- issued March 28, 1916. 'yTheline finder and cord selector switches are alike in all substantial respects.

1 Each comprises a longitudinally movable shaftfrl carrying as many sets of brushes 2 as'there are groupsof stationary terminals to he engaged. To move the'shaft up, an

extension at the lower end of the shaft is brought into engagement with the constantly rotating power member 3 bymeans of an idler wheel operated by the up-drivemagnet 32; and to move the shaft down, theiextension is' brought into engagement with the power member 4 by means of an idler wheel operated by the down-drive magnet 62.

1 and carries as many tripping yokes 7 as there are finder switches in the group. The

trip rod, in rotating, brings all of its trip ping yokes 7 into position to operate the brush controlling cams5 of the correspond ing sets of brushes on all of the switches, so

that which ever of the finder switches is caused to move up has that set of brushes tripped that corresponds with the'particular trip magnet 16, 17, that is at thetime ener-' gized. been in use'is returned to its normal position, any of the associated controlling cams 5 that has been tripped is engagedand 'rotated in a reverse direction to separate its switch springs again and thus render theminactive."

When the finder switch that has" ioo ' Eachof the line finder and cord selectorswitches has'associated with it a commutator 8*Wl110ll OOII1pf'1S6S a number of station- 7 commutator segments and a set of mov-' able brushes carried at the top of the switch shaft 1 and cooperating with the stationary segments. This commutator serves to make and break a number of controlling circuits in the various stages of the upward movement of the switch shaft. i

'For controlling the circuits of the organization, there are employed a-number of sequence switches whichare' shown at different points andare designated 100,200, 300, 4.00 and 500 respectively. These sequence,

switches may be o f the type disclosed in Patent 1,127,808 issued February 9,1915, to.

Reynolds and Baldwin. Each consists an electromagnetically controlled motor or driving; mechanism anda number of asso-i ciated switch cams; The switch camsassociatedwith each of the sequence switches 100 are designated 101 to 103 inclusive; those associated with each ofthe sequence switches 200 arefdesignated 201 to 22am:

elusive; those associated with each of the sequence switches 300 are designated 301- to 310 inclusive; those associated with each of the sequence switches 400 are designated 4:01 to 4:16 inclusive; and those associated with each of the sequence switches 500 are designated 501 to 521 inclusive. To each of the contacts associated with the various sequence switch cams are applied certain numerals. Those numerals in the case of the cams 101, 201, 301, 1-01 and 501 indicate the only positions of the associated sequence switch in which these particular contacts are open; the numerals applied to all of the other contacts of each sequence switch indicate the only positions of the particular associated switch in which the associated contacts are closed.

The sequence switches 100 merely act as timing switches and have only one resting position. The resting positions of the other sequence switches, and the stages of operation with which these positions are associated, are as follows:

, Sequence switch 200.

Normal.

Awaiting starting circuit.

Awaiting starting circuit release.

Hunting calling line.

Awaiting prereding finder circuit.

Awaiting operators selecting circuit.

. Releasing operators selecting circuit.

Hunting cord circuit.

Talking.

. Line finder at tell-tale.

Cord selector at tell-tale line finder returned.

Cord selector returned.

Sequence switch 300.

. Awaiting a call.

Position vacant. Position busy.

Sequence switch 400.

Normal. Listening in. Listening out.

Sequence switch 500.

. Normal. Awaiting listening key sequence switch.

' cated.

causes the energization of a. trip magnet corresponding to the roup of lines in which his line is located. The finder switche each have many sets of brushes as there are groups of lines. circuit'causes a preselected one of the finder switches to move its brushes, and the ergization oi the-trip magnet makes active the set of brushes corresponding with the group in which the calling line is located. The apparatus which brings about the energization oi the trip magnet operates to prevent tent porarily the trip magnets of other groups of lines from beingenergized by calls that may at the time be initiated in the other groups.

As soon as the brushes of the finder switch are tripped, another finder switch is brought into operative relation with the star cir cuit, and then the starting circuit is release". and made available for the use of calli lines in groups other than the group ii. which the first mentioned calling line is lo- That group is deprived of control over the starting circuit until after the finder switch has connected with the terminalsof the calling line. The object of this is to prevent the same calling line from starting a second finder switch in the interval before the calling line is found.

When the finder switch brushes complete connection with the terminals of the calling line, the finder circuit operates certain apparatus that determines to which of a num ber oi. operators positions the connection of the calling line shall be extended. The selection is effected through the medium of selection controlling apparatus that is common to the cord selector switches upon which the finder circuits terminates, and to the operators positions to which these cord selector switches are designed to extend calls. 1V hen a finder circuit is ready to extend a call, it first causes all of the ope-rators positions that are idle or awaiting a call to indicate their receptive condition by operating corresponding switch parts upon the common selection controlling apparatus. The selection controlling apparatus responds by preparing a path for the energization of a cord selector tripping magnet corresponding with the first operators position in the series that is ready to receive a call. The finder circuit that is extending the call then sends a tripping impulse over the path thus prepared. Vhen the tripping magnet operates, the movement of the cord selector switch is started. At the outset of 'the movement the set of brushes is tripped that corresponds with the preselected operators position, and immediately thereafter the common selection controlling apparatus is released and made available for determining the selection of other operators positions by other cord selectors switches and finder circuits.

The closing of the starting After the set of cord selector brushes has 4 been tripped, the brush shaft continues its upward movement, successively engaging the terminals oi the connectlng clrcuits lomad at the operators position that has 1 ceiver which notifies her that her position has been selected and that a call is coming. At the same instant, the listening-in keys associated with all of the connecting cords of the position are rendered inoperative so that the operator cannot interfere with the coming call by listening in on a cord circuit after the position has been selected and before the call arrives.

When the cord selector switch stops on the terminals of the selected connecting Vcircuit, it lights a lamp associated with that circuit on the operators position and at the same time causes the tone, in the operators telephone receiver to cease. Italsomoves' a sequence switch of the selected connecting circuit to bring the operators telephone set into connection with the selected circuit, and

, operates a relay that closes the circuit to the operator.

the operators telephone instantly and in advance of its closure by the sequence switch,

thus saving time in establishing communi-.

cation between the calling subscriber and When the operator has received the call- 7 ing 'subscribers instructions, she tests the line that is called for and, if it is free, inserts the callingplug into the line jack.

This act automatically disconnects the oper-- ators telephone apparatus from the circuit; and the dlsconnectlon of the operators telephone apparatus causes the actuation of they calling cord apparatus to apply ringlng current to the called subscriber s line. Y

While the calling; line and called line are united, the operator can bring her telephone I apparatus into or out of connection with the circuit by pressing the listening-in'key inchinto connection with one of the connecting circuits, the telephone set Is automatically disconnected from any other connect ng circuit with which it may at the. time be in connection.

spring-jack withoutdisturbing the connec-' tion of the calling line with the circuit,--as

. connection.

scribers station. vth1s clrcult energlzes the llne relay 12,

calling line'is a-rnessage-rate line, the operator, beforewithdrawing the plug, presses a charge key which causes a registration upon a meter assoclated'with the hne, and

I which also makes the calling plug ineffectiveto bring about the releaseo'f the connection while the charge key is depressed. Also at the instant of release, a relay arts to prevent any possible reenergization of the line relay of the calling line when that relay is reconnected by the fallingback of itsassociated cut-off relay. 7 i r The operators positions are arranged to receive incoming calls byway of several 3 groups of finder circuits with their associinterference between simultaneous calls originating in different groups offinder circuits, the arrangement being such'that when theselecting apparatus oi one group 'ated cord selector switches and to f )revent acts to select a particular operators posh tion, thatposition is made inaccessible to "the selecting apparatus and finder-circuits of another group. They different operators positions are also so inter-related that the positions are kept equally busy, this being accomplished by rendering each positioninaccessible to incoming calls after it has re. ceived a call or after the operator has super vised an existing connection, and restoring its accessibility only when all of the positions have received a call or supervised a The positions are. then all restored to accessibility excepting such as may at the time be attending to a call or to a connection, or have all of their "cords in use,

or may be out of service by reason'ofthe operator being absent from the position.

The features of the operation that have been set forth in outline in thejforegoing, together with other features presentinfthe system, will be fully explained in the de-.- -tailed description, that follows. H

vidual to the circuit or the listening-out key common to all of the circuits. In pressinga listening-in key, tobring her telephone set" a circuit is closed that extends by way of both windings of the line relay 12 and both limbs of the telephone line, and is completed in the contacts of-the switchhook at the sub- The How of current, in

which, in attracting its armature, applies ground to the conductor 18. This causes current to fiow from battery through the winding 7 of the relay 19, sequence switch contact 103 (10% toli), conductor 18'and ground at the contact of the operated line relay 12.

The relay 19 attracts its armature and closes a circuit that extends from battery through the right-hand winding the associated relay 24, front contact of relay 19, back contact of relay 22 and lower armature and back contact of relay 23 to ground. llelay 24 operates and closes in its left-lu-ind front contact a circuit that extends from battery by way of the winding of the associated group trip magnet 16 and the left-hand winding of the relay 24, in parallel, to the front contact of that relay, and thence by way of conductor 58, the winding of the relay 22, and the lower back contact of the relay 28 to ground.

Current flowing in the circuit traced above operates the trip magnet 16 of the group in which the calling line is located, locks up the relay 24 of the associated group and operates the relay 22 common to all of the groups. The trip magnet 16 rotates its associated trip rod to bring all of the yokes into position to trip the corresponding set of brushes of whichever of the line finder switches is started. The group relay 24 breaks, in its left-hand back contact, the circuit of the conductor 58 to the corresponding relays 24 of the succeeding groups of the series.

The relay 24, in its right-hand front contact, also completes a circuit that extends from battery through the motor magnet of the sequence switch 100, and contact 102 (1813; to 1 1) of that switch. In moving out of position 11:, sequence switch 100 closes its contact 101 and opens its contact 103. As contact 101 is closed in all positions eX- cepting position 1 of the sequence switch, the switch is caused to make one complete rotation; and as contact 103 of the sequence switch is open in all positions excepting positions 18-5,; to 19;, the conductor 18 is held open while the sequence switch is mak .ing its revolut on and until it gets back to position 1. lhe time required by the sequence switch to make one complete rotation is so regulated as to be greater than that occupied -by the line finder switch in finding the terminals of any calling line. The action, therefore, is such as to interrupt the group conductor 18, and hold it open until. after the l ne relay 12 of the calling line has been released as a result of the find ing of that line.

The relay 22, common to all the groups, in operating, opens in its back contact the circuit of the conductor 57, which extends serially through the back contacts of the relays 19 of the various groups. As this conductor 57 is the path over which the relay 19 of any group serves to effect the initial energization of the associated relay 24 and the operation of the corresponding trip magnet, the interruption of this conductor, insures the operation of only one trip magiet and the tripping of only one set of brushes on a started line finder switch.

The common relay 22, in its front contact, completes a circuit that extends from grounded battery through the left-hand 'nding of the finder circuit relay 30 (see Fig. 2), contact 206 (2) of the finder sequence switch 200, conductor 29, front contact of relay 22, through back contact of relay 28, to ground. The conductor 29 has branches extending to like sequence switch cams 206 of all of the finder circuits terminating upon the line finders that have access to the calling line. But, for reasons which will hereinafter be explained, the sequence switch 200 of only one of these finder circuits is standing in its 2 position. In the present instance, it is assumed that this is the sequence switch of the finder circuit F.

As a result of the closure of the circuit traced above, the relay 80 is energized and closes a circuit that causes the associated sequence switch 200 to move out of position 2. This circuit extends from battery through the motor magnet of the sequence switch 200, sequence switch contact 202 (2), righthand front contact and armature of relay 30, sequence switch contacts 208, (18 to 14) and (2 to 7), commutator segment M of the associated cord finder switch CS, and to ground by way of the brush that is in engagement with this commutator segment. Relay 80, in attracting its armatures, also close a locking circuit for itself that extends from battery by way of the resistance coil 56., sequence switch contacts 217 (2) the right-hand winding of the relay 80, sequence switch contacts 216 (2 to 4) and (2 to 9), front contact and left-hand armature of relay 30 and armature and back con-- tact of the relay 8'? to ground.

As a result of the closure of its motor magnet circuit in the right-hand front contact of the relay 30, the sequence switch 200 moves out of position 2 and comes to rest in position in position 3 of the switch, a circuit is closed that extends from battery by way of the rip-drive magnet 32 of the corresponding line finder switch Lll", sequen-i-e switch contact 207 (8 to 4), front contam and right-hand armature of relay 80. sequence switch contacts 208 (18 to 14) and to '7), and to ground by way of the commutator segment M and associated brush of the corresponding cord finder CS. The energization of the lip-drive magnet 32 starts the upward movement of the corresponding elevator rod with its associated sets of brushes. f t the outset of the upward movemcnt of the elevator rod, all of the brush trip levers are moved past the corresponding trip yokes. The only trip magnet that is energized in this case is the magnet 16 which corresponds with the group in which the callinglin is located; and. consequently, the

and the other sets are held clear of their associated line terminals. 7

As soon as'the set oi brushes correspondng with th calling line is tripped, the

s'rou-o aooaratus b means of." which the .i 1 l1 9 lines control" the brush tripping and line tinder starting operation, may be returned to its normal condition; The first step in this restoring operation is effected by the closure of a circuit which 'is' completed by Way-of the K segment of the line finder comtripped.

mute-tor immediately after the brushes are Thls circuit extends from battery, in parallel branches through the relays 23 s and 33(see' Fig. 1), conductor'26, sequence switch contact 209 (2%;to 3), conductor 68, and to ground by way of the K segment of the line finder commutator and its associatedbrush; lhe energization of the relay Iterruptsfln the lower back contact of that relay, the previously described "circuit :that has up to this 'time'i'naintained the energization of the trip magnet 16, the group relay 24cand the common starting relay 22. Relay 23, inits upper front contact, closes a looking circuit for itself and the associated. relay 33 that extends by way of conductor 25 and the sequence switch contacts 210 to 1) of all of the finder circuits in series to ground at a point beyond the last switch of the series.

As has already been stated,normally there is only one of the tinder circuits with its se quence switch in position 2 awaiting: the receipt oi a call. li hen the call comes in, this sequence switch is nnniedlately moved to position 0, inthe mannerdescribed above. Therefore, at thisstac e of the operation, the sequence switches of all of the tinder circuits in position to close'their contacts 210' The locking circuit tor the relays 23 and 33' is, therefore, held closed until another onset the finder circuits has its scquence switch moved into' position 2. This isaccomplished by relay which, in operating, applies aground to conductor '28 to move the sequence switch of another finder circuit out of position 1 and into position 2,- and which also applies a ground to the conductor 2i to move the sequence switch of the apm'opriated finder circuit out of position3. v

Assuming that the sequence switch of iiudcrcir uit F" is in iiosition 1 and that the sequence switch of finder circuit F is in some position between 4: and. 17, that-finder circuit being assumed to be in use, the operation of the relay "completes the following meme; from battery, through the ,motor switch 200 of finder circuit [contacts 211 7 ts 203 (1) of the sequence (3 to .17) and (8 to of the sequence switch 200 of finder circuit F, conductor- 28,

lower contact and armature-cit the relay33 to ground. This causes the sequence switch oiifi'nder circuit F tomoveintoposition 2;

K rby any chance,thesequence switch oi tinder circuit F should fail to be moved into the call-awaiting position 2, when'the relay operates, it will be moved into that position when the sequence switch of the appropriated ii'nder circuit F moves into position'fi at a slightly later stage in the operation. The circuit by which this-result would, un-

der these circumstancegbe accomplished extends from' battery through 'the motor magnet and contact 203 (1) of the sequence switch of finder. circuit F, contacts 211 (1) of that sequence switch, sequence switch contacts 211 (a to 17) and (3 to 17)'otfinder circuit F (assimied to be in use), and thence by way 01'? contacts 222 to 1) of all er the finder circuit sequenceswitches in ser es, to

ground. In otherwordsyat anytime that thefinder circuit sequence swltches are all standing in position 1 or 1n position 5. and

beyond, aground is supplied by wayof the 222 cams in series that moves one of the switches into position 2, and thus places the associated'finder circuit in ltSCiLll-ZIWFLHCIIIQ,

condition. V h h The sequence sw tch of finder'circuitf F 1s moved out of 13081110113 by the closure of a circuit that eiitends from battery through and 38 energized, and these relays. release their armatures. Belay 23, in releasing, re-

ten ds in branches and 58 through the various sets of group relays. thus again giving the roups access to theistarting circuit. 7

At this stage of the operation of the. system, the sequence switcho'l the appropriated finder circuit F'is in position t, and the LF is moving up with the set of brushes tripped that correspondsiwith the group in As the which the calling line. is located. trippedbrushes rise. they come into engage ment consecutively with the sets of terminals corresponding with the difi'erent lines of the.

mores into position 2, it opens in its conta ts 210 the circuit by Way of conduc tor 25 whichhas been maintaining'relays 23 connects to ground the circuit which ex elevator rod of the associated line'finder group. At the instant otengagement of the 7 brush 42 with the correspondlng'llne ter-" minal 46 of each line, a circuit is closed that extends from'battery by way of the relay 52, sequence switch contacts 212 (2 to 4), conductor 50, brush 42, line terminal 46, conductor 53 and winding of cut-oil relay 11 to ground. It a line is busy as a calling line, branch path is in existence for the flow of current through the cut-off relay 11 by way of contacts 212 of another finder circuit sequence switch, and associated resistance 64 if the switch is in positions 4% to 12%, or windings of associated relays 30 of the finder circuit and 155 of the connecting cord circuit it the switch is in positions 12% to 14. It the line is busy as a called line, a branch path is in existence by way of the windings of relays 119 and 175 associated with the connecting circuit calling plug (see Fig. In either case, this branch path serves to shunt the relay 52 and prevent its operation as the finder brushes pass over the terminals of the corresponding line.

If the line over the terminals of which the brushes are passing is not busy, the relay 52' is operated, andin attracting its armatures closes a circuit that extends from battery through the lower winding of the relay 37, front contact and lower armature of the relay 52, sequence switch contact 213 (2 to 4), conductor 49, brush 41, line terminal 45, condutcor 39 to one limb of the-telephone line, thence by way of the path controlled in contactsof the substation switchhook,,to the otherlimb of the line, conductor 88, terminal 44, brush 40, conductor 48, sequence switch contact 214 (2 to 4), upper armature and "front contact of the relay 52, upper winding of the relay 37 to ground. The circuit traced above is not completed until the finder switch brushes engage the terminals of the calling line, as the calling line is the only line that has its telephone receiver oil the hook, and at the same time is not conne ted with either by some other line finder or by a connecting circuit calling plug. The completion of this circuit energizes the relay 37 and causes that relay to interrupt in its back contact the circuit by way of the lefthand armature and front contact of the relay 30, sequence switch contacts 216, right-hand winding of relay 30, sequence switch contacts 217, and resistance 56 to battery, which had been holding relay 30 locked up from the moment that relay was first energized upon the receipt of the call. Y

Relay 30, in releasing its armatures, breaks its ownlocking circuit traced above, and also breaks the previously traced path including sequence switch contacts 208, righthand front contacts ofthe relay 30 and se quence switch contacts 207, over which current has been fiowing'to energize the updrive magnet 32 of the line finder. Therefore, the operation of the relay 37, upon the finding ot the calling line, acts to effect the instant denergization of the up-drive magnet 32 and thus to stop the brushes upon the terminals of the calling line.

In order that the brushes may always be stopped in registration with the line terminals, the locking circuit of the relay 30 has an alternative path to ground by way of sequence switch contact 215 (2 to 4), conductor 66, the C segment of the line finder c0mmutater and the corresponding brush to ground. The C segment of the commutator is so formed and related to its brush that the connection between the two is interrupted only when the corresponding line brushes on the elevator rod are in engagement with cor responding set of line terminals. The unlocking of the relay 30, and the consequent stopping of the upward movement of the elevator rod, can therefore occur only when the line brushes are in proper relation to the terminals of the callingline.

When the relay 30 is deenergized, as a result of finding the calling line, it also completes a circuit that extends from battery through the motor magnet and contacts 202 (3 to 4) of the sequence switch 200, righthand back contact and armature of the relay 30, sequence switch contacts 208 (18 to 14) and (2 to 7), conductor 79, segment M of the cord finder commutator and its corresponding brush to ground. The closure of this circuit moves the sequence switch out of position 4.

When the sequence switch reaches position 42;, it closes a path for the flow of current through the cut-ofi relay 11 of the calling line by way of resistance coil 64, sequence switch contact 212 (4% to 121 conductor 50, brush 42, line terminal 46 and conductor 53. The fiow of current in this path operates the cut-off relay 11 to disconnect the line relay 12 from the circuit, and that relay, in releasing its armature, disconnects ground from' the common conductor 18. The times oi operation of the various parts are so related that the line relay 12 is deenergized, in the manner described above, before the timing sequence switch 100 of the associated line group has completed its rotation and closed the circuit or" conductor 18 in sequence switch contacts 103. The current which previously flowed through the cut-oil relay 11 by way of the winding of relay 52 of the finder circuit had been insuflicient to operate the cutbfii relay by reason of the winding oi relay 52 being of relatively high resistance.

The brushes of the line finder switch are now at rest in engagement with the tern1inals of the calling line, the group starting circuit represented by the conductors 57 and 58 and the associated common relay 22 has been released and is in readiness to respond to another calling line, and the sequence switch of another finder circuit has been switch contact 218 (5 to 8), conductor 67,

commutator segment M of the line finder switch and corresponding brush to ground. The operation of the relay 55 applies ground to the conductors 81 extending to all of the operators positions to the connecting circuit terminalsof which the cord finder switch or" the finder circuit hasaccess. At each of the 7 positions where the operator is at her station and is inreadinessito receive a call, the

'a ssociatedrelay 91 (Fig.4) is inert, and the operators telephone sequence switch 300 is in its 1 position.- Consequently, at each of s such positions, a circuit is'closed that extends from battery through the winding of the associated relay 92, left-hand armature and back 'contact'of relay '91, sequence switch contact 304 1 conductor 81 armature and front contact of relay 5 5 to ground. The relay 92 of each awaiting position attracts its armature and closes a circuit that extends from battery through the front contact and armature of the relay 92 to the conductor 82, and thence to ground by way of the windings of a number of relays 77 of which one-is 7 provided for each cord finder frame that has access to thisparticular operators position. The particular nature of this connection of the different operatorscircuits to aplurality of finder frames will be explained later.

i F or the. present,.the operation will, be described merely in its relation to the particular finder frame that serves the finder 01rcuit that has been assumed to have been appropriated by the calling line; For the present it will also further be assumed that the operators' position Ois in readiness to receive a call.

The finder circuit sequence switch 200 does not stop in position 5, but continues its movement and'comes to; rest, in position 6.

Here it awaits the closing of a circuit the completion of which is dependentupon the condition of the other finder circuits or the associated group. 'This circuit extends from battery through thele'ft-hand winding of the relay 30, contact 219 (6) of the appropriated finder circuit sequence switch, contacts219 (9 to 4) of the sequence switches of the associated finder circuits preceding it in the series,-conductor 76, outer armature and back contact of relay 54 and right-hand back contact and armature of relay 61 to ground, This circuit is open either in cam 219 of'a'preceding findersequence switch 200 in the series, or in contacts of the relays 54 or 61 as long as any other sequence switch of the series is in same-position between po sitions 4 and 9. That is, it' is open from the time the line finder switch of any associated finder circuitfinds acalling line untilthe jcord finder switch 01 that circuit has moved far enough to trip the brushes correspond.

ing with the selector group. Not until this has'occured will the above-traced'circuit of the awaiting finder circuit be closed. 7 1 The closure of this circuit causes relay 30 to attract its arinaturesandcomplete a circuit that extends from battery through the. motormagnet and sequence switch contact 1202 (6) Off the sequence switch 200, front contact and right-hand armature of'relay 30, sequence switch contacts 208 (18 to '14) and (2 to 7 conductor 7 9,00mmutatorsegment M of the cord finder and corresponding brush to ground. t The completion of this circuit moves thefinder sequence switch out of position V v 7 When the finder sequence switch reaches position'6i}, it closes a circuit thatex tends from battery through the windingof relay 54, (Fig. 3),1eit-hand back "contact and'armature of relay'61', conductor 7 3, findersequence switch contact 218 (6-;to 8), conductor 67 ,conunutator segment M of the line finder switch and corresponding brush to ground. Relay 54 attracts its armatureandx completes a branch of the circuit traced above which extends from conductor 73' by way of the armaturevand back-contact of the relay 63, front contact and inner armature n of relay 54, armature and front 'contactof relay 77 (whicl1 relay is energized, as previ ously described,"as a result of the corre-' sponding ope'rators position being in readiness to receive a call), right-hand-bacl'r contact and switch spring of relay 93 of the I correspondinggroup, winding of associated relay 94, winding'of relay "93, left-hand.

switch spring and resting contact-of relay 93, conductor 83, left-handbackcontact and'armatureof relay 95 at the corresponding operators position to battery. Upon the closure of the above-traced branch circuit,

the group relays 93 and' 94 are energized in parallel with the relay 54. Relay 93, in operating, disconnects its own energizing winding and that of relay 94 from the previously-traced path tobattery by way of the left-hand back contact and armature of the relay 195,and connects-them in a path which extends from battery-by way of the windi ing of the relay 95 and conductor 84. This causes the relay 95 also to be energized and to interrupt, in its left-hand armature and backcontac-t, the path by way of conductor.

83 over which the relays 93 and 94 were 7 I initially energized. P Relay 94, in operating, closes a clrcuit from: battery through" the winding of the trip magnet 22 of the group corresponding to the selected operators position and to ground by way of the right-hand armature and front contact of the relay 941. This relay also closes a circuit that extends from battery through the winding of the relay 63 and the left-hand armature and front contact of the relay 94: to ground. The relay 63, in operating, closes a branch that eX- tends from the conductors 73 (grounded at commutator segment M of the line finder switch) through the armature and front contact of relay 68, conductor 72, sequence switch contact 220v (7), and left-hand winding of relay 80 to battery. Relay 30 attracts its armatures and closes a circuit that extends from battery through the motor magnet and sequence switch'contact 202 (7), front contact and right-hand armature of relay 30, sequence switch contacts 208 (18 to 14:) and (2 to 7), and thence to grounc by way of the M commutator segment of the cord finder switch. The closure of this circuit moves sequence switch 200 out of position 7. Furthermore, relay 30, in operating, is locked up over a circuit that extends from battery through resistance 56, sequence switch contacts 217 (2 to 9), right-hand winding of relay 30, sequence switch contacts 216 (7 to 9) and (2 to 9), front contact and left-hand armature of relay 80 and armature and back contact of relay 37 to ground.

V'Vhen the sequence switch reaches position 8, it closes a circuit that starts the upward movement of the brush-carrying rod of the cord finder switch, this circuit extending from battery through the updrive magnet 84- of the cord finder, conductor 89, sequence switch contact 207 (8 to 9), righthand front contact and armature of relay 30, sequence switch contact 218 (8 to 9), conductor 67, commutator segment M of the line finder and corresponding brush to ground.

At the outset of the upward movement of the cord finder brush rod, the tripping levers of the various sets of brushes are brought simultaneously into operative position with respect to the corresponding tripping yokes, and that set of brushes is tripped and made operative whose trip magnet is at the time energized. In the present instance, it is assumed that this is the trip magnet 22 associated with the terminals of the group of connecting cord circuits extending to the 0 operators position.

Immediately after the set of brushes is tripped, the common operators selecting circuit is restored so as to be available for the use of other cord finder switches. This is effected through the medium of a circuit that is completed by the grounding of the K segment of the cord finder commutator, this segment being so located as to be engaged by its brush immediately after the tripping levers of the sets of brushes pass the associated tripping yokes. The circuit referred to extends from battery through the winding of relay 61, conductor 74, sequence switch contact 221 (7-1- to 8), conductor 80, cord finder commutator segment K'and its corresponding brush to ground. Relay 61, in operating, opens, in its lefthand back contact, the previously-traced circuit by way of conductor 78 which, up to this time, has been holding energized the relay 95 at the O operators position. and the relays 93 and 94 corresponding to this position on the cord finder frame. The release of the relay 9% deenergizes the corresponding trip magnet 22 and the common relay 63. lhe deenergization of the relay 93 reestablishes, subject to the release of relay 61, the control of other finder circuits over the brush tripping mechanism of the associated cord finder frame. It also restores the corresponding operators position to operative relation with the common selecting apparatus of other finder frames, in a manner which will hereinafter be explained.

Delay 61, in operating, closes a locking circuit for itself by way of conductor 73, sequence switch contact 218 to 8), conductor 67, commutator segment M of the line finder and corresponding brush to ground. It also completes a circuit that extends from battery through the motor magnet and contact 205 (8) of the sequence switch 200, conductor 75, right-hand front contact and armature of relay 61 to ground. T he closure of this circuit moves sequence switch 200 out of position 8. In moving out of position 8, the sequence switch opens its contacts 218 to 8) and 221 (7 to 8), thus deenergizin relay (31 and again extending conductor 78 to the relay and conductors over which the opei tors seis effected. in closing its right-hand bacl: contact upon release, relay 61 also re stores the continuity of conductor 76 and makes it available for moving out of position 6 the sequence switch of some other finder circuit which may be waiting for access to the operators selecting circuit.

When the sequence switch 200 is moved out of position 8, it moves into position 9 and there awaits the finding of an idle connecting cord circuit upon the operators position that has been assigned. As the brushcarrying rod moves up, the brushes 111, 112, 118 and 114 of the set that has been tripped come into engagement successively with setsof terminals 115, 116, 117 and 118 corresponding with the different connecting cord circuits located at that operators position. When cord circuit is not in use, its corresponding terminal 118 is connected directly to ground; and when the terminals of such. a connecting circuit are encountered,

a circuit is completed that extends from bat tery through the lower winding of relay 37, sequence switch contacts 206 (8 to 9), conductor 99, brush 114, terminal 118, conductor 88, sequence switch contact 404 (1), righthand back contact and armature of'relay 119 to ground. Current flowing in this circuit causes the relay 37 to attract its armature and break the previously traced circuit by way of sequence switch contacts 216 and 217 and the right-hand winding of relay 30, which, up to this time, has been holding relay 3O energized. It may here be noted that the locking circuit of relay 30 has a branch to ground in parallel with the branch controlled in the back contact of relay 37, the

' the cord finder switch to come to rest.

branch referred to extending by wayoi sequence swltch contact 215 (8 to 9), conductor 78, commutator segment C of the cord finder switch and the corresponding brush toground. This path serves the same function as has already been described in connection with the path by way of the 0 segment of the line finder commutator; that is, it prevents the relay 37 from causing the.

deenergization of the relay 3O excepting when the brushesot the cord finder switch are centered upon-their successively engaged sets of terminals.

When the relay is released, as a result 01. the brushes engaging the terminals of a connecting circuit that is not in use, it opens, in its right-hand front contact, the previously traced circuit including the up-drive magnet 3 1, and thus causes the brushes of The relay 30, in releasing, also closes a circuit that extends from battery through the motorfmagnet and contact 202 of the se 'quence switch 200, back contact and righthand armature of relay 30, sequence switch contact 218 (8 to 9), conductor (37, M segment of the line finder commutator and corresponding brush to ground. The closure of this circuit moves the sequence switch 200 out of position 9. V

It has previously been explained how, when the sequence switch of an appropriated finder circuit reaches position 6%, it operates a particular trip magnet on the cord finder frame that corresponds with a waiting operator s positiomand at the same time opcrates the relay 95 associated with the app aratusat that operators position. When the relay 95 at the operators position attracts its armatures, it closes a circuit which extends from battery through the motor magnet'and contact 303 (1) ofthe operators sequence switch 300, conductor 12]., righthand front contact and armature. of-relay 95, conductor 123. right-hand front'contact and armature of relay 125 to ground. The closure otthis circuit causes'the operators sequencezswitch 300 to move out of positi0n1. I

It may be well at this point .to explain that the operators sequence switch, as. indicated by the numerals applied to sequence switch cam 301, is adapted to rest in three positions,-namely, positions 1, 4 and 17. The energizing circuit of the relay 125 is controlled in local contacts 127 of the-operators telephone jack 126. VVhen the op erator is at her position, these contacts are closed and the relay 125 is energized. At

such a time, a circuit is closed that extends from battery through the motor magnet'and contact 303 (slot the operators sequence switch and the left-hand frontcontact and armature of relay 125 to ground. Theretore,while the operator is ather station it is impossible for the operators sequence cally moved out of positionsl and 17, and

can rest only in position 41-. i

lVhen the operators sequence switch moves out of position 1 as a, result of the selection of the operators position and the actuation of relayj95, a circuit isrlosed that extends from battery through the winding of relay 145, upper back contact and armature of relay 153, sequence switch contacts sea (2 to.16),'outerback contact and armature of relay 1 12, sequence switch contact 305 (1 to 16) sequence switch contact and right-hand iront contact and arn'iature of As 7 a result of the flow oi": current in this circuit, the relay 1415 relay-125 to ground.

attracts its armature and closes a circuitthat extends from the device 1 13 for producing a characteristic tone, through a. ondenser 14 1.;

right hand front contact and armature of relay 14-5 and winding 146 of the" induction coil of the operators telephone set 147 to ground. The result, theretore is that an instant after the operators sequence switch is moved out of positionhas a result of the selection of that particular operators position by theseelnng finder circuit, a call tone.

is applied to the operators telephone receiver which warns the operator. that her position has beenselected and that a call'is coming. I

The manner in which the selection of an idle cord'cireuit is accomplished. by the is ing' cord finderswitch. and*themanner in which such selection moves the finder sequenre switch 200 out of position-9, whence it moves into position 1 1, have already been described. As long as the finder sequence qua Due.

switch 200 is in position 9, the conductor extending from the third or sleeve brush 42 of the line finder is connected with battery by way of sequence switch cam 21 and resistance coil 64, to hold the cut-off relay 11 of the calling line energized; and the conductor 98 extending from the third or sleeve brush 113 of the cord finder switch is open at sequence switch cam 217. When the linder sequence switch reaches position 9?}, it closes circuit, which will be traced hereinafter, for the energization of relays 151, 154 and 157 of the connecting cord circuit. This last-mentioned circuit is maintained until the finder sequence switch 200 moves out of position 11, when it is interrupted in contacts of cam 217. An instant later, in position 12 of the sequence switch, the cam 217 acts-to extend the sleeve conductor 98 through the right-hand winding of the relay 30 to contacts of the cam 212, which are closed a moment later in position 12% of the sequence switch In moving from position 121; to position 12%, the sequence switch 200, by the action of cam 212, substitutes the path last referred to by way of the right-hand winding of the relay 30 for the path by way of the resistance coil 64, over which, up to this moment, the cut-off relay 11 of the calling line had been maintained energized. From the moment the finder sequence switch 200 reaches position 12%, therefore, the cut-off relay 11 and the relay 30 of the finder circuit are included serially in a circuit that maintains their energization, and as long as the continuity of the circuit is maintained, the finder circuit is held in its talking condition.

a As was stated in the foregoing, when the finder sequence switch 200 reaches position 99 after the brushes of the cord finder switch have come to rest upon the terminals of the idle connecting cord circuit, a circuit is completed for the energization of relays 151, 154 and 157 of the connecting cord circuit. This circuit may be traced from battery through the windings of relays 151, 154 and 157 in parallel (the branch through the windingof relay 157 also passing through Contacts 509 of the calling cord sequence switch 500) to sequence switch contacts 505 (1), and thence by way of lis tening-key sequence switch contacts 405 (1), left-hand back contact and armature of re lay 152, conductor 87, contact 117 and brush 113 of the Cord finder switch, conductor 98, sequence switch contacts 217 (9% to 14) and (9?;to 11), and resistance coil 36 to ground.

Therefore, an instant after the idle connecting cord circuit has been appropriated and the finder sequence switch 200 'moved out of position 9, the three relays 151, 154 and 157 of the connecting cord circuit are operateds ,Relay154, operating, closes, in its armature and front contact, a locking circuit for all three of the relays, which circuit extends by way of calling cord sequence switch contacts 506 (1), and listening key sequence switch contacts 406 (1 to 6) to ground. The three relays are thus held locked up while the listening-key sequence switch 400 is mov ing from its normal position 1 to its listen-- ing-in position 7. This movement of the listeni11gkey sequence switch is effected by a circuit that extends from battery through the motor magnet and contacts 403 (1) of the sequence switch 400, sequence switch contacts 507 (17 to 8) and (1) and right-hand front contact and armature of relay 154 to ground. In leaving position 1, the listeningkey sequence switch 400' breaks, in contacts 405 (1), the connection of the sleeve conductor S7 with battery by way of the windings of relays 151, 154 and 157. But relay 151, in operating, has in the meanwhile completed a circuit that extends from battery through the winding of relay 152 and outer front contact and armature of relay 151 to ground. As a result, relay 152 is energized and in its left-hand armature and front contact has disconnected the conductor 87 from the branch extending by way of sequence switch contacts 405 (1), and has connected it instead with battery by way of the lefthand switch spring and resting contact of relay 156 and the winding of relay The relay 155 thereupon operates to close the circuit of the talking conductor 86 which is normally maintained open for a reason which will hereinafter be explained.

fter relay 152 is initially energized by the operation of the relay 151, it is maintained operated by a path to ground that is closed by way of cam 407, as soon as the listening-key sequence switch reaches position 2 and thereafter until it moves out of its listening-in position 7.

When the relays 151 and 157 operate at the moment the idle connecting cord circuit is seized, they effect certain changes in the condition of the operators telephone circuit, which will now be described. hen relay 151 operates, it closes a circuit that extends from battery through the winding of relay 153 of the operators circuit (see Fig. 4), conductor 129, calling cord sequence switch contact 502 1), and inner front contact and armature of relay 151 to ground. Relay 153 operates, and in its upper armature and back contact opens the circuit over which, up to this moment, the relay 145 had been maintained energized. Relay 145 thereupon releases its armature, and opens the circuit, previously traced, over which the calling tone from the device 143 had theretofore been supplied to the operators telephone apparatus. The ceasing of this tone in her telephone notifies the operator that the incoming call has been extended one of her connecting cord circuits. Vhich of the conby the flashing of the lamp 161 associated. 'with that cord.

The circuit by means of which this is effected extends from battery through the resistance'163, lamp 161, calling cord sequence switch contacts 514 (1 to 2), listening-key sequence switch contacts 412 to 189 and call signal interrupter 162 to ground. The lainp is thus caused to flash as soon as the listening-key sequence switch moves into position 1%}. 4

Relay 157, in operating, at the instant the cord circuit is seized, connects the operators telephone set with the telephone of the calling subscriber. This circuit may be traced from the operators telephone apparatus by way of conductors 135and136, conductors 167 and 168*, calling cord sequence switch contacts 512 (1) and 513 (1) and correspondin inner contacts and armatures of relay 15 calling cord sequence switch contacts 510 (1) and 511 (1), conductors 169 and 170, back contactsand armatures of relay 158, conductors 85 and 86, terminals 115 and 116- and corresponding brushes 111 and 112 of the cord finder switch, cord finder conductors 96 and 97 ,finder sequence switch contacts 214 (95ito 14) and 213 to 14), linefinder conductors 48 and 49,'line finder brushes 40 and 41 and correspondingline terminals 44 and 45, and liner conductors 38 and 39 to the telephone apparatus at the calling station, V

Thecircuit between the operators telephone and the telephone at the calling subscribers station is completed the instant the connecting cord is seized. At the same instant, as previously described, the relay 154 ojperatesto close the circuit for moving the 1 position. to move until it reaches position 7, where' listening-key sequence switch 400 out of its Sequence switch 400 continues it comes to rest. Justjbefore the sequence switch reaches position 7, it opens the circuit, by way-of sequence switch contact 406 (1 to '6), and left-hand armature and front contact ;of relay 154, over which the relay 157 and its associated relays 151 and 154, had been held energized; and at the same moment, it completes an alternative path for the connection of the operators telephone with the calling "subscribers telephone. This alternative path extends fromthe operators telephone apparatus'147 by way of conductors 135 and 186, resting contacts of the ring- 7 back key 160 and the coin-return key 159,

listening-key sequence switch contacts 408 (6't0 8) and 409 (6to 8), and resting con tacts and armatures of relay 158 to'the conductors 85 and 86, whence the circuit is as previously traced to the'calling subscribers line and telephone apparatus. The connection between conductor 136 and conductor being energized 86 also includes contacts of the relay 155 which are closed at this time, the relay 155 over a path previously traced. i ii 1 V d When the listening-key sequence switch reaches position 7, therefore, the bypath to the operatorstelephone by way of the con-' 'tacts of relay 157 is opened, and-the main path'by way of the sequence switch contacts 408 (6 to 8) and 409(6 to 8) is closed. The object of providing the bypath closed in stantly by the relay 157 upon the seizure of the connecting cord circuit, isto save the time required for the sequence switch 400 to close the direct path "byway of its cams communication with the calling subscriber a little sooner than wouldbe the caselif'the establishment of the circuit waited upon the movement of the sequence switch, In the operation of a system such as" that herein disclosed where the traflic is heavy, the resultant saving of time of the operator and the calling subscriber, although slight, is of tors 135 and136, including'the resting contacts of the coin-return key 159 and the ring-back key 160, conductors 165 and 166, and listening-key sequence switch contacts 410 (6 to'8) and 411 (6 to-8); From this point, the circuit of the talking conductors extends to opposite poles of the battery by way of two windings of the cord circuit repeating coil 169, thefother two windings of the repeating coil being included' in conductors that extend from the poles of the battery to the tip and ring contacts respecapparatus hereinafter to be described is operated. V

tively, of the calling plug 170, when certain correspondingrepeating coil'windings, in-

cludes the, winding of the'answering supervlsoryrelay 171, so that in position 7 of the listening-key sequence switch, the supervisory'relay 171 is included in the circuit that extends to the calling-subscribers line and station. This relay controls the'illumination of theanswering supervisory lamp 17 2 by controlling a shunt about'the lamp including the resistance 173. 'When the listening-key sequence switch moves out of po-' sition 1, upon the seizure of the cord circuit,

80 408- and 409', and thusplace the operatorrin it closes a circuit that extends from battery through resistance 174, answering supervisory lamp 172 and sequence switch.contacts 407 (13; to 18%;) to ground. The current flowing in this circuit tends to light the lamp 172; but the illumination of the lamp is prevented by the fact that the answering supervisory relay 171 is energized over the circuit which at this time is closed at the calling subscribers station. The answering supervisory lamp 172 is thus shunted and prevented from lighting.

When the operator is informed, by the cessation of a call tone in her telephone receiver and by the lighting of the call lamp 1.61 that she is connected with the calling line, she speaks to the calling subscriber and ascertains the number of the line with which he desires connection. She then lifts the calling plug 170 of the connecting cord identified by the flashing call lamp 161, and tests the line with which connection is desired by touching the tip of the plug to the sleeve of the corresponding spring-jack 14. Assume that the called line is similar in its equipment and circuit connections to the lines which are illustrated in Fig. 1. In this case, the tip, ring and sleeve contact portions of the spring-jack 14 are connected with conductors 38, 39 and 53, respectively, which extend to the stationary terminals 44, 45 and 46 of a finder switch. If the called line is busy, by reason of the brushes of a finder -switch being in engagement with these terminals, battery is applied to the finder switch terminal 46 of that line and by way of conductor 53. and its multiple connectionspto the sleeve of the corresponding spring-jack 14. When the sequence switch of the finder circuit is standing in position 4%; to 124,-, battery is applied by way of the resistance coil 64 and sequence switch cam 212. N hen the se quenee switch 200 is standing in positions 12% to 14, battery is applied by way of the winding of relay 155 ot the connecting cord circuit. Tn case the line with which connection is desired is busy as a called line, battery is applied to the sleeve of the tested springjack by way 01'"? the windings or relays 119 and 175, the sleeve of the calling plug 170 of the cord circuit that is already connected with the line, and the multiple connection between the sleeve of the spring-jack that is connected with and the sleeve of the springjack that is being tested.

When the tip of the calling plug 170 is touched to the sleeve of the spring-jack of such a line, current fiows by way of the tip of the plug, right-hand armature and back contact of relay 175, conductor 133 and windin g of the operators test relay 184 to ground. This relay, in attracting its armature. closes a circuit that extends from battery through a "retardation coil 185, front contact and armature. of relay 184 and winding 146 of the induction coil of the operators telephone set 147 to ground. The closure of this circuit causes a click in the operators telephone receiver which notifies her that the line is busy. The operator may then tell the calling subscriber that the called line is busy, and release the connection by pressing her master listening-key 186. The manner in which this effects the release will be described hereinafter.

If the called line is not in use, there will be no battery connection with the sleeve of the tested jack, and no click will be produced in the operators telephone receiver. Consequently, she will insert the plug 170 into the spring-jack 14. The insertion of the plug in the jack closes a circuit that extends ;trom battery through the windings of the relays 119 and 175 in series, and thence by way of the registering sleeve contacts of the plug 170 and spring-jack 14 to ground by way or" the winding of the cut-off relay 11. The cut-off relay 11 disconnects the line relay 12 from the circuit. The relay 175, in its right-hand armature and back contact, disconnects the tip of the plug from th conductor 133 extending to the operators busy test relay 164, and connects it instead with the tip conductor of the talking circuit. Relay 175 also closes a circuit that extends from battery through the motor magnet and contacts 503 (1) of the calling cord sequence switch, contacts 413 (7) of the listening-key sequence switch, left-hand front contact and armature of relay 175 and normally closed contacts of the charge key 176 to ground. The closure of this circuit energizes the motor magnet and moves the calling cord sequen e switch out of position 1. When the calling cord sequence switch reaches position 9., it comes to rest and completes a circuit that extends from battery through the motor magnet and contact 403 (7) of the listening-key sequence switch, .ontact 515 (2) of the calling cord sequenc switch, and right-hand back contact and armature of relay 154 to ground. When the listening-key sequence switch 40 moves out or position 7 as a result or" the closure of this cirr-uit, it completes a circuit that e):- tends from battery through the motor magnet and contact 504 (2) of the calling cord sequence switch, contact 413' (8 to 15) of the listening-key sequence switch, left-hand front contact and armature of relay 175, and resting contact of the charge key 176 to ground. The closure of this circuit moves the calling cord sequence switch out of position 2.

its the listeningkey sequence switch 460 moves out of position 8, it operates its cams 408.. 409, 410 and 411 to disconnect from the connecting cord circuit the loop that eX- tends to the operators telephone circuit by way of the conductors 135, 136 and 165, 166,

l and connects the talking conductors 85 and 86 of the connecting cord circuit directly 7 through to' the left-hand windings of the repeatlng 0011 169..

Furthermore, in moving out of position 7 it interrupts the branch 1 of the energizing circuit of the cord circuit holding relay 152 that had been completed tor ground by way of listening-key sequence switch contacts 407 (2 to 7), and leaves the continued energization of the holding relay dependent upon a path to ground that e);- tends by way of the right-hand front contact and armature of relay 152 and contact 508 1 1- to 173;) of the calling cord sequence switch. I a

After the calling cord sequence switch 500 is moved out of position 2 by the movement of the listening-key sequence switch out of "switch rin in current is an lied to the position 7, as described above, it moves through its various stages until it reaches position 12, at which point a circuit is closed that extends from battery through the winding of relay 180,'left-hand armature and back contact of relay 178, armature and back contact of relay 177, sequence switch contacts 507 (12 to 13) and (10 to 15), sequence switch contacts 516 (3 to 13) to ground. The closure of this circuit ener- 'gizes relay 180 and causes it to open in its right-hand armature and back contact a o hby Way f t t 504 (4 t 13) f relay 178 prevents the reestabhshment of the calling cord sequence switch, which theretofore had maintained the energiza tion of-the motor magnet of that switch. As the cam 501 of the calling cord sequence switch iscut so as to keep the energizing circuit of the motor magnet closed in position 12 of the sequence-switch, the switch continues to, move until it reaches-position 13, where it comes to rest. 7 P

In position 13 of the calling cord sequence connecting cord circuit toring the bell at the called subscribers station; This is, effected through the medium of a circuit which has two branches alternately closed in the rotation of the commutator 182, one or" the branches including the battery and the other including a source of ringing current 181. From the commutator 182, the

circuit extends byway of sequence switch contact 517 winding of relay 177, lefthand armature and front contact of rela 180-, sequence switch contact 519 (13) ,"ring contact of the calling plug 170, ring spring o'f'the spring-jack 14, and thence over. the 1 corresponding side of theline to the called Y subscrlbers station, where 1t is connected to ground by way of the substation condenser and'bell. At the same time, the other side of the called subscribers line is connected directly to ground by way of sequence also, by the diversion of a small part ofthe alternating current by Way of the condenser 1'83and the upper right-hand winding of. the repeating coil 169, indicates to the calling subscriber the application of ringing current to the lineof the called subscriber. When the called subscriber, respondingto the ringing of the bell, takes his telephone receiver from its hook, the resultant closure of a relatively low resistance path "across the limbs of the line causes an increase 1n the current flow over the ClIC'Lllt just traced and brings about the energization of the relay 177;. This relay is preferably so constructed and adjusted, in any well-known way, as to make it insensitive tothe' alternating current flow that passes through 'it during the ringing of the bell,

but responsive to the current flow that takes place when the telephone receiver is taken from its hook. 7

When the relay 177 operates, it opensthe short circuit that normally exists aboutthe winding of the relay 178, which relay is included in the path previouslytraced through the relay 180 and cams 507 and 5160f the calling cord sequence switch. The removal 0 of the short circuit causes relay 178 to attract its armatures. 'The opening or the left handarmature and back contact of the the short circuit about the Winding of relay 178 when the armature of relay i177 falls back after a momentary attraction. The

engagement of the right-hand armature of relay'17 8 with its front contact closes a path 'relay180 is shunted and releases its armatures. The left hand armature o'frelay180, infalling back, opens the previously traced path overwhich ringing current was applied to the connecting cordcircuit} The right-hand armature of relay180, in re- 7 leasing and closing lts back contact, vcloses a circuit that extends from'battery through the motor magnet and contact 50 1 e to 13) of the calling cord sequence switch. This causes the sequence switch to move outof position 13.' i

The calling cordsequenceswitch '500 is indicated as being adapted, after leaving position 2, to "come to rest in positions 4-,

5,7,8, 10-and' 11, as fwellas in position 13 V as-describedv above. These positions of the sequence switch may be employed for'the purpose'orf effecting the application to the.

connecting circuit-ct ringing currents of different characteristics for t epurposeof selectively ringing the bells'of party lines. The movement of the sequence switch in' andthrough these positions may be under the control of a branch of the energizing circuit of the relay 180 which eXtends to a cam 520 of the calling cord sequence switch, and may be further controlled by a branch of the energizing circuit of the motor magnet of sequence switch 500 which is adapted to be closed in positions 4., 7 and 10 of the sequence switch cam 50%. The application of partly line ringing current to the con-- necting cord circuit may be effected through the medium of contacts of the calling cord sequence switch cams 518 and 519, closed in positions 5, 8 and 11. .The particular method in which this is accomplished is disclosed and claimed in my Patent 1,251,60a issued January 1. 1918, but inasmuch as this is a feature with which the present inven tion is not concerned, it is not herein shown.

lVhen the calling cord sequence switch leaves position 13, it moves to position 16. In this position, a circuit is completed that extends from battery through the lower right-hand winding of the repeating coil 169, calling supervisory relay 187, sequence switch contact 519 (16 to 17 engaging ring contact surfaces of the calling plug 170 and called line spring-jack 14, thence to the called subscribers station, over one limb of the line, through the substation apparatus and back over the other limb of the line to the engaging tip contact surfaces of the spring-jack 1d and calling plug 170, righthand armature and front contact of relay 175, sequence switch contact 518 (1 1 to 17) and upper right-hand winding of the repeating coil 169 to ground. The current flowing in this circuit energizes the calling supervisory relay 187 and causes it to close a circuit that extends from battery through the motor magnet and contact 503 (16) of the calling cord sequence switch. and armature and front contact of relay 187 to ground. This moves the sequence switch out of position 16, whereupon it moves to position 17, which is the talking position.

Up until this moment, the lamp 161, which, as described, was caused to flash when the call first came in, has been burning steadily as a ringing lamp, the circuit for its illumination being to ground by way of contact 516 (3 to 16) of the calling cord sequence switch. When the sequence switch moves out of. position. 16, this circuit is interrupted and lamp 161 is extin uished. At the same time, a circuit is closed from battery through rcsistancecoil 1188, and thence by way of two branches, one of which extends through the calling supervisory lamp 189, left-hand front contact and armature of relay 119 and sequence switch contact 521 (17) to ground and the other one of which extends by way of resistance coil 190, sequence switch contacts 51 1 (17), and armature and front contact of relay 187 to ground. The resistance in thelatter branch is low, as a result of which the calling supervisory lamp 189 is shunted out as long as the calling supervisory relay 187 is energized.

When this stage has been reached in the operation of the system, the talking circuit is complete between the calling subscriber and the called subscriber. The finder circuit sequence switch 200 is in position 14:, the connecting cord sequence switch 590 is in position 17 and the listening-key sequence switch is in position 15, the listening-our position. In this condition of the circuit, the calling subscriber has control over the answering supervisory lamp 172 through the medium of the answering supervisory relay 171, and the called subscriber has con trol over the calling supervisory lamp 189 through the medium of the calling super visory relay 187. As long as both sul. scribers have their telephone rccei ers oil the switchhoolrs, these lamps are dark. l Vhen either one of the subscribers hangs up. the corresponding lamp is lighted. W hen both lamps light at the same time, the operator knows that the conversation is at an end and takes down the connection.

The operator disconnects by removing the calling plug 170 from the spring-jack of the called. subscribers line. This act permits relays 119 and 175 of the connecting cord circuit and the cut-off relay 11 of the called subscribers line to fall back. The cut-oft" relay 11, in falling back, reconnects the line relay 12 with the called subscribers line. Relay 119, in releasing its right-hand armature to engage its back contact, reconnects ground with the conductor over which the cord finder tests the cord circuit. But the test conductor 88 is not made continuous to ground, and the cord circuit is therefore not .made selectable until the listening-key sequence switch cam 10 1 is closed upon the return of that sequence switch to its 1 po-- sition. The other armature of the relay 119, in disengaging its front contact, extinguishcs the calling supervisory lamp 189.

Relay 175, in permitting its left-hand armature engage its back contact, completes a circuit that extends from battery through the winding of relayv 157, sequence switch contacts 512 (2 to 17), left-hand back contact and armature of relay 175, and resting contacts of the charge lrey 176 to ground.

Relay 157, in operating, closes a locking circuitfor itself that extends by way of sequ'ence'switch contacts 5.12 to 17), inner front contact and armature of relay 157, and sequence switch contact 510 (2 to 17) to ground. Relay 157 also closes a circuit that extends from battery through the motor magnet and contact (2 to 17) of the calling cord sequence switch, outer front contact and armature relay 157, and sequence switch contact 511 (2 to 18), to ground. The closure of this clrcuit moves 

